Step 1: Heat 2 tablespoons of olive oil in a large pot over medium heat. Add the chopped onion and sauté for a few minutes until soft and translucent.
Step 2: Stir in the minced garlic and cook for 1 minute until fragrant.
Step 3: Add the chopped carrot and celery. Cook for several minutes, stirring occasionally, until they begin to soften. Stir in the chopped red bell pepper and cook for another minute.
Step 4: Pour in the 1 cup of canned diced tomatoes. Season with salt and black pepper to taste, and stir well.
Step 5: Add the rinsed and drained beans and the sweet corn.
Step 6: Pour in enough water (or vegetable broth) to cover all the vegetables (about 4 cups).
Step 7: Cover the pot with a lid and let the soup simmer over low heat for about 30 minutes, until the vegetables are completely tender.
Step 8: Turn off the heat and stir in the finely chopped fresh parsley.
Step 9: Serve hot with a generous squeeze of fresh lemon juice and a slice of crusty bread.